If CircSidebar is set and you hit /cgi-bin/koha/circ/returns.pl, you will get "ReferenceError: $ is not defined"
I can confirm the error, but haven't been able to locate the mistake in the code yet. Only thing I notice is some errors from the validator - 2 stay </div> tags.
(In reply to Katrin Fischer from comment #2)
It needs to be moved to a separate JS file or a JS file which is already included on the affected pages. It's on my to-do list but someone else can take it if they want.
As far as I know it's only a cosmetic issue -- the highlighting of the current page won't work.